Thermally responsive valve assembly

ABSTRACT

A thermostatic valve assembly includes three housing components (16, 18, 20) containing two interconnected chambers (64, 78). A first thermally responsive valve unit (68) is disposed in the chamber (64) while a second thermally responsive valve element (98) is disposed in the chamber (78). Both the chambers (64) and (78) have inlets (60, 110) and the chamber (64) has an outlet (66). The valve may assume configurations allowing a minimal flow (FIG. 2), a large volume warm up flow (FIG. 3), a mixed flow regimen (FIG. 4) and a pure cooling flow regimen (FIG. 5).

This is a division of application Ser. No. 08/928,927 filed Sep. 12,1997.

FIELD OF THE INVENTION

This invention relates to valves, and more particularly, to a thermallyresponsive valve assembly.

BACKGROUND OF THE INVENTION

German patent publication DE-AS 23 14 301 discloses a thermostatic valveunit having two thermally responsive valves located in a divided housinghaving inlet and outlet openings. The housing accommodates compressionsprings that bias the thermally responsive valve elements towardspredetermined positions. The housing is a casting which incorporatesconnectors for the inlet and the outlet and the parts are assembled bymeans of threaded connectors. Seals are included where appropriate.

The thermally responsive valves carry valve disks for opening andclosing against valve seats dependant upon temperature of the fluidflowing into the housing.

Such units are frequently employed in vehicular applications for watercooled engines. In these applications, such valve units may preventcoolant from traveling to the radiator, for example, during a cold startof the engine so that the engine coolant will rapidly heat and allow theengine to warm up promptly. The rapid warm up also permits rapid heatingof a passenger compartment for the vehicle as well. After somepredetermined temperature is reached, the coolant is then permitted toflow through the radiator to be cooled so as to maintain the coolantgenerally at the predetermined temperature which is an optimumtemperature for engine operation.

To perform these functions, the valve unit is located in connection withthe coolant line passing to and from the engine and to the coolant pumpfrom the vehicular radiator as well as optionally from the heater corein the passenger compartment. The coolant lines are typically connectedto fittings formed on the valve housing.

Many of these units are difficult to install and, because of the metalcasting used as a housing, have an undesirably high weight which impactson fuel economy. Further, as they are typically designed as the mainthermostatic control valve for coolant flow, they frequently are toolarge and unwieldy for other applications where lesser flow rates areinvolved. Thus, German patent application DE-PS 44 16 240 discloses avalve that is reduced in size and weight through the use of a plastichousing. This disclosure is not of a valve unit having two thermallyresponsive valves, but rather, one with but a single thermallyresponsive valve. Consequently, such a valve does not have the abilityto operate in an emergency in many applications as, for example, whenthe thermally responsive valve fails. Furthermore, the thermallyresponsive valve has a valve member on the valve body for opening andclosing of flow openings, and consequently, is unduly complex.

Other thermally responsive valve units have been proposed but mosttypically require electrical control and incorporate a variety ofrelatively complex elements that are used to assure operations in anemergency situation. Again, simplicity is lacking.

The present invention is directed to overcoming one or more of the aboveproblems.

SUMMARY OF THE INVENTION

It is the principal object of the invention to provide a new andimproved thermally responsive valve assembly. More specifically, it isan object of the invention to provide such a valve assembly that islight in weight and simple in construction. It is also an object of theinvention to provide such a valve assembly that is simple and yetremains operative in the event of an emergency situation involving afailure of some part of the valve assembly.

An exemplary embodiment of the invention achieves the foregoing objectin a thermally responsive valve assembly that includes a housing. Twoconnected chambers are located within the housing and two spaced inletsare disposed in the housing, one to each chamber. An outlet from thehousing is provided and is fluidly connected to one of the chambers. Afirst thermally responsive valve is located in the one chamber for a)closing the inlet to the one chamber for a first temperature conditionwhile allowing fluid communication between the two chambers, b) openingthe inlet to the one chamber for a second temperature condition whilepreventing fluid communication between the two chambers, and c) openingthe inlet to the one chamber while allowing fluid communication betweenthe two chambers for at least one third temperature condition betweenthe first and second temperature conditions. Also included is a secondthermally responsive valve in the other of the chambers which isoperable to a) allow a first-flow rate between the two chambers for afourth temperature condition and b) allow a second flow rate between thetwo chambers for a fifth temperature condition.

In a preferred embodiment, the first thermally responsive valve controlsmixing of the fluid entering the housing through the inlets and thesecond thermally responsive valve is a temperature responsive choke forfluid flow between the two chambers.

One embodiment of the invention contemplates the use of a spring fornormally biasing a first valve member forming part of the firstthermally responsive valve toward a position closing the inlet to theone chamber. The second thermally responsive valve also includes aspring which normally biases a second valve member toward a positionrestricting flow between the chambers.

A highly preferred embodiment contemplates that the housing be definedby three components. Two of the housing components each contain one ofthe chambers and the third housing component connects the two chambers.Bayonet slots connect the two housing components to opposite sides ofthe third housing component.

In one embodiment of the invention, a valve seat is located in the thirdhousing component for cooperating with the second valve to control flowbetween the two chambers. A restricted bypass passage extends about thevalve seat.

The invention contemplates that the housing have a generally cylindricalouter surface provided with seal receiving grooves. Preferably, theouter surface is provided with an outwardly directed positioning nose.

The thermally responsive valves each include a body with a plungerextending therefrom and movable with respect thereto. A centering tip isdisposed on each of the plungers. In the usual case, the body willcontain a quantity of a wax that expands or contracts with temperaturechanges to extend or retract the plunger.

In one embodiment, each of the chambers includes a centering ringconnected to the housing by angularly spaced arms. The centering tips onthe plungers are received in an associated one of the centering rings.

In such an embodiment, each of the chambers, oppositely of theassociated centering ring, includes axially extending guide surfacesslidably engaging the body of the associated thermally responsive valveso that the body itself acts as a valve member.

In another aspect, a valve assembly is provided that includes a housingmade up of first, second and third housing components. The first andthird housing components sandwich the second housing component and aflow passage is located in the second housing component. Valve chambersare disposed in each of the first and third housing components andvalves are located in each of the chambers. Springs in each of thechambers bias the associated valve towards a predetermined positiontherein and additionally bias the first and third housing componentsaway from the second housing component. A connector at the interface ofthe housing components is provided for holding the housing components inassembled relation against the bias of the springs.

In a highly preferred embodiment, there is an interface between thefirst and second housing components and another interface between thesecond and third housing components. The connector comprises bayonetslot connections at each of the interfaces.

Other objects and advantages will become apparent from the followingspecification taken in connection with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a coolant reservoir with the thermallyresponsive valve assembly of the invention installed therein;

FIG. 2 is a sectional view of the thermally responsive valve assembly inone flow configuration, allowing minimal flow through the valve;

FIG. 3 is a view similar to FIG. 2 but showing another flow conditionwherein the valve is allowing substantial flow;

FIG. 4 is a view similar to FIGS. 2 and 3 but illustrating a conditionwherein two flows are mixed within the valve assembly;

FIG. 5 is a view similar to FIGS. 2-4 inclusive but illustrating stillanother flow condition wherein mixing is precluded;

FIG. 6 is a side elevation of a thermally responsive valve actuatoremployed in the invention;

FIG. 7 is an exploded view of three housing components which, in turn,are shown in section; and

FIG. 8 is a sectional view of one housing component taken atapproximately 90 degrees from the view shown in FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a preferred embodiment of a thermally responsivevalve assembly made according to the invention employed in the coolantcirculation system of a vehicle. However, it should be understood thatthe invention can also be used in other contexts as, for example, fuelor oil circulation systems or anywhere else where flow rate are to becontrolled within stipulated temperature ranges. As illustrated in FIG.1, a vehicle coolant reservoir 10, typically formed of plastic or thelike, includes a chamber 12 which may be molded in place and which isadapted to receive the valve assembly, generally designated 14, of theinvention. The valve assembly 14 includes a housing made up of threecomponents including a first housing component 16, a second housingcomponent 18, and a third housing component 20. As seen in FIG. 1, thesecond housing component 18 is sandwiched by the first and third housingcomponents 16 and 20 and includes a cylindrical surface 22 provided witha peripheral groove 24 for receipt of an O-ring seal 26.

A generally cupped shaped containing element or cap 28 fits about thefirst and second housing components 16, 18 and is sealed against thechamber 12 by means of an O-ring seal 30. In addition, slits 32 in thechamber 12 align with slits 34 in the cap 28 to receive a springretainer 36 to hold the cap 28 in place. The cap 28 may include an inletopening 40 at its bottom and a side outlet opening 42 adjacent to thefirst housing component 16. An inlet (not shown) from the reservoir 10to the interior of the chamber 12 adjacent the third housing component20 may also be provided.

Turning now to FIGS. 2-5, the valve assembly 14 will be described ingreater detail. The first housing component 16 includes a cylindricalsurface section 50 including a radially outwardly opening peripheralgroove 52 for receipt of an O-ring seal 54 which may seal against theinterior of the cap 28. At its lower end, an inlet port 56 is providedwhich aligns with the opening 40 in the cap 28. A centering ring 58 isdisposed in the center of the opening 56 and held in that location byintegrally formed radially extending arms 60 which, of course, areangularly spaced to provide flow passages to define the inlet 56. Avalve seat 62 surrounds the inlet 56 and faces into a chamber 64 withinthe third housing component 16.

The outlet passage 42 in the cap 28 is alignable with an outlet 66 in aside of the third housing section 16. The outlet 66 connects to thechamber 64.

Within the chamber 64 is a first thermally responsive valve element 68.The lower end 70 of the valve element may seat against the seat 62 toprevent fluid from entering the chamber 64 through the inlet 56. Theupper end 72 of the valve element 68 may enter and seal against a port74 within the second housing component 18 to close off a passage 76which normally connects the chamber 64 to a chamber 78 within the thirdhousing component 20.

Intermediate the ends 70 and 72, the valve element 68 includes ashoulder 80. A compression coil spring 82 abuts the shoulder 80 as wellas a recess 84 in the second housing component 18. The spring 82 biasesthe valve element 68 towards the seat 62 and additionally tends to biasthe housing components 16 and 18 away from each other for purposes to beseen.

The second housing component 16, above the port 74, includes a centeringring 88 located in place by a number of integrally formed angularlyspaced radially extending arms 90 similar to the arms 60. A peripheralseat 92 is located at the radially outward extremity of the upper sidesof the arms 90 and in turn is surrounded by an annular recess 94. At onelocation, the seat 92 includes a groove or slot 96 to allow acontinuous, but restricted bypass flow of fluid past the seat 92.

A second thermally responsive valve element 98 is located in the chamber78 and has a shoulder 100 intermediate its ends 102 and 104. Acompression coil spring 106 is abutted against the one end of thechamber 78 and against the shoulder 100 to bias the second valve element98 toward the seat 92 to close the flow passage within the secondhousing component 18 interconnecting the chambers 64 and 78 except forthe groove or slot 96.

The upper end of the third housing component 20 includes an inlet 110which may be in fluid communication with the interior of the chamber 12and the reservoir 10.

Turning now to FIG. 6, a representative thermally responsive valveelement that may be used for both the valve elements 66 and the valveelement 98 is illustrated. The valve element 66, 98, includes a body 112which typically will be a container of a wax having a relatively largecoefficient of thermal expansion. A plunger 114 extends into the body 12and as the wax within the body 112 expands in response to an increase intemperature, the plunger 114 will progressively emerge from the body112. If the temperature decreases, the quantity of wax within the body112 will decrease in volume with the consequence that the plunger 114will be retracted. The plunger 114 is provided with a centering tip 116which is received within the associated centering ring 58, 88 dependentupon whether the valve element is being utilized as the first valveelement 66 or the second valve element 98. This serves to align the ends70, 102 with seats 62, 92, respectively.

Each valve element 66, 98, adjacent to the upper ends 72, 104, includesa cylindrical surface 118 for guiding purposes. As seen in FIG. 7, thesecond housing component 18, on the side thereof facing the chamber 64,includes four equally angularly spaced guide projections 120 (only threeare shown) which embrace the cylindrical surface 118 to guide the end 72of the valve element 68 into and out of the port 74. When the end of 72is within the port 74, it will be appreciated that fluid communicationbetween the chambers 64 and 78 is halted. This is as shown in FIG. 5.However, when the end 72 is spaced from the port 74 as is shown in FIGS.2-4, inclusive, fluid flow from the chamber 78 to the chamber 64 betweenthe fingers 120 is permitted.

The opening 110 in the third housing component 20 includes dependingfingers 122 which serve to slidably embrace the cylindrical surface 118on the valve element 98 to guide the same. In this case, the end 104 ofthe second valve element 98 never seals against the seat but movessufficiently close to the opening 110 as to throttle flow through theinlet defined thereby when in the position illustrated in FIGS. 3-5inclusive. In the position shown in FIG. 2, full flow through the inlet110 is allowed.

Still referring to FIG. 7, it is to be observed that the second housingcomponent 118 includes a radially outwardly directed projection 124.This projection can be used to align in a slot 126 (FIG. 1) in the cap28 to assure that the components of the valve assembly 10 are properlyaligned with components such as the outlet 42 in the cap 28.

The invention also includes unique means for securing the housingcomponents 16, 18, 20 together against the bias of the springs 82, 106.The upper end 130 of the first housing component 16 is provided withtwo, equally angularly spaced L-shaped recesses or slots each having avertical component 132 and a horizontal component 134. The lower end 136of the second housing component 18, in turn, includes two equallyangularly spaced, radially outward directed projections 138 which aresized to snuggly fit in the vertical sections 132 of the slots 130 aswell as in the horizontal sections 134 thereof. Those skilled in the artwill recognize that each set of the components 130, 132, 134 and 138thus defines a bayonet slot whereby the second housing component 18 mayhave the projections 138 inserted in the vertical sections 132 of theslots and moved downwardly to align with the horizontal sections 134 andthen twisted to lodge the projections 138 under shoulders 140 defined bythe upper surfaces of the horizontal sections 134.

The second housing component 118, near its upper end 142, includessimilar radially outwardly directed projections 144. In this case, threeof the projections 144 that are equally angularly spaced, are employed.The lower end 148 of the third housing component 20 is provided withthree L-shaped slots 150 each having a vertical component 152 and ahorizontal component 154. Again, the projections 144 are sized to snuglyfit within the vertical components 152 as well as the horizontalcomponents 154 of the corresponding slot 150 and lodge, upon twisting,against the shoulder 156 in each of the slots 150.

It will be immediately appreciated that another set of bayonet slotconnections is defined and that such bayonet slot connections hold thehousing components 16, 18, 20 in assembled relation against the bias ofthe springs 82, 106 as mentioned previously. This bias, of course,assures tightness of the bayonet slot connections.

Referring now to FIGS. 2, 7 and 8, the structure surrounding the seat 62will be described. Oppositely of the outlet opening 66, and radiallyoutward of the seat 62 is a depression 160. At the same time,immediately adjacent the outlet opening 66 and radially outward of theseat 62 is a step 164. As can be seen in FIG. 8, which, it will berecalled, is a section taken at 90 degrees to the section shown in FIG.7, merging surfaces 166 extend from the depression 160 to the step 164.

The purpose of this construction is to insure that the first valveassembly 68 is well bathed in the fluid entering the inlet 56 so that itaccurately responds to the temperature thereof. As viewed in FIG. 4,fluid entering the inlet 56 is required to pass below the bottom side 70of the first valve element 68 toward the depression 160 which isdirectly opposite from the outlet 66. As a consequence, the fluidnecessarily must flow entirely around the first valve element 68 so thatit will be essentially at the temperature of such fluid.

FIG. 2 illustrates the configuration of the components relative to oneanother with a low volume flow rate, as might be employed during thestart up phase of a vehicle. Specifically, heated coolant will beretained within the engine and/or the heater core and only a smallvolume of heated water may be diverted elsewhere as, for example, topreheat transmission fluid. Specifically, warmed coolant enters theinlet 110 to the chamber 78 and flows about the second valve element 98to the annulus 94 about the seat 92. From there it flows through theslot or groove 96 and between the fingers 120 and the upper end 72 ofthe first valve 68 to the outlet 66.

Another configuration of the components is illustrated in FIG. 3. Inthis case, the second valve element 98 has been warmed by heated coolantsufficiently that its plunger 114 has extended to lift the bottomsurface 102 off of the seat 92. As a consequence, there will be freeflow of heated fluid through the chamber 78 past the seat 92 andultimately between the fingers 120 and the upper end 72 of the firstvalve element 66. This flow will exit the valve through the outlet 66while passing about the first valve unit 66. Generally speaking, a stopmay be utilized to limit upward movement of the second valve element 98to the position shown in FIG. 3.

FIG. 4 shows still another configuration of the components. In thiscase, the second valve element 98 is in the same position as illustratedin FIG. 3. The flow past the seat 92 has been sufficient to bring thefirst valve element 68 up to a temperature whereat its plunger 114 hasbegin to emerge from the bottom surface 70. As a consequence of thisconfiguration, flow may occur past the seat 92 and between the upper end72 and the fingers 120 toward the outlet 66. However, it may also occurpast the seat 62 from the inlet 56 with a consequence that the two flowswill mix within the chamber 64.

FIG. 5 illustrates the components in a pure cooling phase where allcoolant is circulated to, for example, a radiator to be cooled. In thiscase, the upper end 72 of the first valve element 68 is blocking theport 74 precluding flow from the inlet 110 to the outlet 66. On theother hand, the lower end 70 of the first valve unit 68 is now at amaximum distance from the seat 62 so that all inflow from the inlet 60passes to the outlet 66.

When the vehicle is shut down, the coolant will gradually cool to theambient temperature causing the wax within the valve unit 68 and 98 todiminish in volume. At this time, the springs 82, 106 will assure thatall components are returned to the configuration illustrated in FIG. 2.

For typical vehicular operations, it will be desirable that both thefirst valve element 68 and the second valve element 98 operate atroughly the same temperature, for example, 80° C. It will be appreciatedthat the operation is such as to handle even emergency situations inthat should either one of the valve elements 68 or 98 fail, there willalways be a flow path open, either from the inlet 110 to the outlet 66via the slot 96 or from the inlet 56 to the outlet 66 past the valveseat 62.

It will also be appreciated that a valve made according to the inventionis easy to fabricate and may be made of plastic housing components toreduce cost and weight. And the unique use of three housing componentscoupled by bayonets slots against the bias of springs provides an easymeans of assembly while assuring that the components are fixed relativeto one another.

We claim:
 1. A valve assembly comprising:a housing made up of first 16,second 18 and third 20 housing components, said first and third housingcomponents sandwiching said second housing component; a flow passage insaid second housing component; valve chambers in each of said first andthird housing components; valves in each of said chambers; springs ineach of said chambers biasing the associated valve toward apredetermined position therein and biasing the associated first or thirdhousing component away from the second housing component; and aconnector at the interface of said housing components for holding thehousing components in assembled relation against the bias of saidsprings.
 2. The valve assembly of claim 1 wherein there is an interfacebetween said first and second housing components, and an interfacebetween said second and third housing components and said connectorcomprises a bayonet slot connection at each said interface.
 3. The valveassembly of claim 1 wherein at least one of said valves is a thermallyresponsive valve and said housing has an inlet to and an outlet from thechamber containing thermally responsive valve and surrounded by a valveseat, said thermally responsive valve being biased toward said seat bythe associated spring; said outlet being to one side of said inlet; andfurther including a depression partially about said seat at a locationremote from said outlet and a step partially about said seat at alocation adjacent said outlet.
 4. The valve assembly of claim 3 whereinsaid step and said depression merge into one another.